1. Technical Field
The present invention relates to a construction and a method used in the production of satellites or carrier rockets for launching satellites, the inventional construction being intended to form a part included in a satellite and a carrier rocket, respectively.
2. Background of Related Art
Satellites and carrier rockets for launching satellites should for reasons of fuel economy have a weight as low as possible while maintaining a strength and rigidity that is sufficient to allow the intended load to be carried. A material making it possible to fulfil these requirements is carbon fibre composite. The type of carbon fibre composite generally used for the production of parts for satellites or carrier rockets comprises two parallel, thin layers of carbon fibre and a core of a lightweight material arranged between these layers. In order to give a good axial strength of the satellite/carrier rocket despite the small thickness of the layers of carbon fibre, which layers should be as thin as possible in order to limit the weight of the satellite/carrier rocket without for that sake jeopardizing the rigidity, said layers are built up of carbon fibres having a high rigidity. A disadvantage with these rigid carbon fibres is that they are brittle. Ring-shaped parts of aluminium are generally used for the attachment of the parts made of carbon fibre composite.
In the production of constructions for satellites and carrier rockets the constructor is regularly confronted with the problem of joining rotationally symmetrical parts made of said type of carbon fibre composite, such as for instance cylinders and cones, with ring-shaped parts of aluminium. This can be accomplished in different ways. Gluing is most optimal as regards weight and rigidity. A problem with the utilization of glue joints is however that the aluminium and the carbon fibre composite in question are extremely incompatible in thermic respects, since the aluminium has a high coefficient of linear expansion whereas the carbon fibre composite has a low coefficient of linear expansion. The satellite and the carrier rocket are subjected to large temperature variations during the launch, and due to the large difference in thermic linear expansion between the aluminium part and the part of carbon fibre composite the glue joint between said parts has a tendency to break up by the temperature variations. As a consequence hereof, one is often obliged to use bolted joints for joining said parts. A disadvantage with bolted joints of the type used today in these situations is however that they are inferior to glue joints as regards rigidity and that they furthermore require an expensive and complicated co-machining of the aluminium ring with the carbon fibre composite. In order to improve the rigidity, the bolt joints are often supplemented with glue joints, which brings about an extra working operation, which further increases the production costs.